Common Anion Analysis by U.S. EPA 300.0 & 300.1

Among the common anions, fluoride, nitrate and nitrite are enforceable regulated contaminants that are on the National Primary Drinking Water Regulations (NPDWR) standard list while fluoride, chloride, and sulfate, which affect the water taste and odor, are on the secondary regulation list. The Maximum Contaminant Level (MCL) for fluoride, nitrate, and nitrite are 4 ppm, 10 ppm, and 1 ppm, respectively.

For inorganic disinfection byproducts (DBPs), chlorite and bromate are currently regulated with an MCL of 1 ppm and 10 ppb, respectively. Although chlorate was required to be monitored for public water systems during the period of Unregulated Contaminant Monitoring Rule 3 (UCMR 3), no regulatory determination on chlorate has been made.

EPA Method 300.0 was developed in the mid-1980s for compliance monitoring of common anions in drinking water. In 1992, the method was also approved for wastewater common anion monitoring under the National Pollution Discharge Elimination System (NPDES) permits program, although wastewater samples need pretreatment and filtration before loading to the ion chromatograph. EPA Method 300.0 was modified in 1993 to add the inorganic disinfection byproducts as part B. But after a lower level of bromate (10 ppb) was promulgated in the disinfectant and disinfection byproduct stage 1 rule, the EPA Method 300.0 was modified to EPA Method 300.1 to meet the new quantitation requirement.